The present invention relates to a tandem type alternator for a vehicle.
An alternator for a vehicle includes a compact tandem type alternator having a plurality of sets of stators and rotors in order to meet an increasing power demand and to improve mountability on a vehicle.
In the tandem type alternator for a vehicle, a plurality of rotors are arranged in tandem along a rotational shaft and stators are arranged outside the rotors to surround the rotors, and the rotors and the stators are accommodated in a housing.
Ventilation holes for passing therethrough external air are formed in the housing at the axially opposite end walls thereof. As the rotors rotate, an air flow from the ventilation holes in one end wall to those in the other end wall is generated by vanes attached to the rotors and by vanes mounted on the rotational shaft outside the housing so that cooling of the interior of the housing may be attained.
However, in the tandem type alternator for a vehicle, since the plurality of sets of stators and rotors are arranged axially in tandem, axial ventilation resistance is increased and it is difficult to have sufficient air flow produced. Further, since the tandem type is intended to attain miniaturization, it is impossible to provide a sufficient gap between stator windings wound on adjacent stators.
As a result, it becomes difficult to sufficiently dissipate heat generated in the stator windings within the housing to the outside of the housing. Particularly, during the summer season, for example when atmospheric temperature is high, heat is apt to stay within the housing, so that it becomes difficult to achieve sufficient power generating capability in spite of the circumstances where particularly high power consumption is needed.